This invention relates to a method and apparatus for the treatment of thrombosis, venous insufficiency, stimulation of blood circulation, and the like, and in particular to an Automated Compulsory Blood Extraction System (ACBES) configured to provide an efficient and safe means for the measured extraction of blood utilizing a device providing, in effect, an artificial leech, but without the infection, control, care, and other limitations associated with the medicinal leech.
The preferred embodiment of the present invention utilizes recent micro technological advances to provide a micro mechanical device which mimics and improves upon the bloodletting properties of the medicinal leech utilizing a micro mechanical valve, drive pump, and micro sensor arrangement cooperating with a tertiary jaw array having teeth situated thereon.
The preferred embodiment of the present invention contemplates an extraction device which may have a head size of one centimeter or less, and which may be utilized in number about the affected area of the patient to provide controlled, precision, pulsed blood extraction via vacuum induction, supplying a controlled dosage of anticoagulant, histamine anesthetic, or the like.
Alternative embodiments of the present invention includes an independent, single needle, stationary design configured primarily for emergency use, a multi-needle piston design, a large extraction area array design including concentric needles of adjustable depth, and a deep extraction needle design, providing various configuration blood extraction systems designed for a variety of specialized operations.
While medicinal leeches (Hirudo Medicinalus) have been utilized for treating a variety of ailments for hundreds of years, medical science has yet to provide a device which surpasses the effectiveness of the leech for certain applications, hence their continued extensive use in medicine today for stimulating circulation and related treatments.
Even today, the most commonly reported method for restoring circulation to damaged tissue has been through the use of medicinal leeches. In spite of the limitations, the leech has remained the best and only means of compulsory blood extraction for the purpose of stimulating circulation in tissue having restricted circulation.
The lack of control variables such as flow rate, flow pressure, vacuum magnitude, fluid injection and total extraction volume limits the physicians ability to tailor the extraction via vacuum induction, supplying a controlled dosage of anticoagulant, histamine anesthetic, or the like.
Alternative embodiments of the present invention include an independent, single needle, stationary design configured primarily for emergency use, a multi-needle piston design, a large extraction area array design including concentric needles of adjustable depth, and a deep extraction needle design, providing various configuration blood extraction systems designed for a variety of specialized operations.
While medicinal leeches (Hirudo Medicinalus) have been utilized for treating a variety of ailments for hundreds of years, medical science has yet to provide a device which surpasses the effectiveness of the leech for certain applications, hence their continued extensive use in medicine today for stimulating circulation and related treatments.
Even today, the most commonly reported method for restoring circulation to damaged tissue has been through the use of medicinal leeches. In spite of the limitations, the leech has remained the best and only means of compulsory blood extraction for the purpose of stimulating circulation in tissue having restricted circulation.
The lack of control variables such as flow rate, flow pressure, vacuum magnitude, fluid injection and total extraction volume limits the physicians ability to tailor the extraction process for each individual application. Also, bacteria in the leech gut the can be transferred to a patient, adding complications to an already critical state.
The leech is generally used only as a last resort for reestablishing circulation to tissue threatened with hypoxia due to the absence of blood flow. There are many cases where the leech would be used by physicians if it had reliable operation characteristics and there was no chance of infection.
Devices which may have some pertinence to the present, searched for invention may include:
U.S. Pat. No. 5,368,034 teaches a system for facilitating thrombolytic therapy including a sensor monitoring blood flow rate, and alarm means for indicating blood flow above a predesignated rate.
U.S. Pat. No. 5,163,926 teaches a suction metering and mixing device for collecting body fluids, including blood, and simultaneously mixing an anticoagulant therewith.
U.S. Pat. No. 5,037,407 teaches an xe2x80x9cElectronic Monitoring System for Drainage Devicexe2x80x9d comprising a monitoring system for monitoring body fluids passing through, detecting and indicating when a bubble is sensed therein.
U.S. Pat. No. 4,998,919 teaches a xe2x80x9cThrombectomy Apparatusxe2x80x9d comprising first and second lumens enveloping, and an additional chamber in the second lumen having a longitudinal passage for enveloping a safety change wire therein.
U.S. Pat. Nos. 5,141,501 and 5,163,926 teaches a xe2x80x9cSuction Metering and Mixing Devicexe2x80x9d comprising a device having a chamber for controlling the flow of anticoagulant into a suction wand, said wand further including a first suction tube, and second anti-coagulant tube.
Notwithstanding many attempts at replacing the leech with mechanical devices and the like, some of which are taught above, medicine has yet to find a suitable replacement.
An article published in Medical Update (May 1995) by E. W. Brown estimates 65,000 leeches are used each year for medical purposes. These applications are restricted to the limited xe2x80x9clast resortxe2x80x9d cases, since the leech has an inherent unreliability and promotes a possibility of infection.
As indicated the utilization of a medicinal leech in medicine has its shortcomings; for example, the medicinal leech can be used for relieving vascular occlusion but not arterial occlusion, since the latter case has a high risk of infection from bacteria transferred from the leech. Thus, an artificial leech which would be sterile, thus can be used in arterial occlusion cases. This limitation of medicinal leeches, as well as other cases reported in literature, indicate the number of case applications for the artificial leech is expected to expand beyond the current range of medicinal leech use. Brown (1995) reports that leeches are used for over 5000 cases per year. This number would be greater if the treat of infection and the unreliable nature of the creatures could be eliminated.
The medicinal leech as seen a resurgence in use for practical application as a means of restoring circulation to damaged tissue. In the 1960""s, British surgeons began applying the leech to post operative regions of sutured tissue to encourage blood flow. After surgery, some tissues will not be able to drain blood due to venous blockage. The practice became prevalent in America after Dr. Joe Upton used leeches to restore circulation to a reattached ear in 1986. The leeches were credited with saving the ear since the low drainage pressure of venous system was unable to restart circulation. Publication of this success brought the acceptance of leeches as an essential means of restoring circulation to damaged limbs.
Leeches are common through out the world. They all are parasites that prey on warm blooded animals. The medicinal leech (hirudo medicinalis) is of particular use because of its size and the minimal wound it produces. A leech can survive for nearly a year without feeding. Medical practice has found that six months of starving a leech leaves them strong enough to attach themselves immediately upon introduction to the patient.
The leech has the following desired characteristics for the surface extraction of blood:
1) the leech can be placed near the wound site by a medical attendant,
2) the size of the leech head (about 1 cm in diameter) allows for close attachment at the edge of a closed wound,
3) the leech jaws scratch a shallow wound in the skins surface which produces no scaring,
4) the leech injects a histamine and an anticoagulant that aid in opening clogged capillaries,
5) the blood drained by the leech is drawn mainly from the venous capillaries, when finished, the leech detaches itself.
The overall advantage of the leech is that it draws the venous capillary blood that results in the unclogging of the local circulatory passages and thus restores blood circulation to the damaged tissue.
There are limits to the use of leeches due to their arbitrary behavior and desire to only feed themselves and then leave the host. The limits on leech use include:
1) the leech can be placed close to a desired site but not placed exactly at a particular point,
2) leeches carry a bacteria that can infect a patient and lead to further complications as described by Haycox et al in 1995,
3) the possibility of infection limits the types of cases and patients the leeches may be used on;
4) the rate of blood extraction can not be controlled;
5) the leech only drinks about 2 cc of blood then detaches requiring multiple leech use in succession for extended blood extraction,
6) the physician has no feedback information from the leech to verify the restoration of circulation.
In cases of poor circulation, the medicinal leech (Hirudo Medicinalis) is applied to the skin over the effected area allowing the creature to attach itself and withdraw blood at will. The leech is seeking only to feed itself but in the process it benefits the patient by encouraging blood flow into a restricted region. The damaged tissue is typically the result of an amputation. A detached limb can be surgically reattached without fully enabling the circulatory system. There are other means of tissue damage that lead to decreased circulation. Without the circulatory system fully functioning the tissues are insufficiently supplied with nutrients leading to tissue death.
Historically, the medicinal leech was used to extract what was believed to be bad blood from an ill patient. This misconception has been corrected in modern times. The use of the leech to withdraw blood from a tissue region with poor circulation has proven to be essential for saving damaged and reattached tissue.
Only one species of leech is used in medicine. This creature has been well studied to provide doctors with reliable information on leech actions. The leeches are raised in a sterile environment. A leech can live for months without being feed. When the leech reaches a certain age, it is considered to be the right size for use in blood extraction. A starving leech is used to ensure quick action. The leeches are used on a patient only once, then they are destroyed.
Referring to FIG. 7, the leech head has four main sections: the lip which forms an air tight seal, the buccal tissue region which supplies secretion to the attachment site, the jaws that form a Y shaped wound and the throat which expands to form a vacuum and drain the extracted blood. When attached the leech head is about one centimeter in diameter. Each jaw piece is roughly one to two millimeters in length with about 50 teeth.
The application of a leech to preform blood extraction in a clinical environment occurs as follows:
1) A starved leech is removed from its colony.
2) The leech is placed on the skin at the site intended for blood extraction.
3) The leech attaches to the skin by a posterior sucker.
4) The leech attaches its anterior sucker to the skin. (The anterior end is the leech""s head that has the jaw, throat and secretion tissue.)
5) A low pressure region (vacuum) is formed in the leech throat by muscular expansion.
6) The tissue around the jaw secretes a liquid form of an anesthetic, histamine and anticoagulant.
7) The jaw (all three of the jaw sections) is pressed against the skin surface and is xe2x80x9crockedxe2x80x9d to produce a sawing action.
8) A wound is formed in the skin by the sawing action.
9) The low pressure around the center of the jaw draws blood from the wound.
10) After the throat cavity is filled, the leech ingests the crop.
11) The pressure relief from the injection allows a back flow of the excreted fluid into the wound. (The vacuum is reduced over the wound during injection but is not entirely released.)
12) The jaw is maintained in pressure against the skin with teeth extending into the wound without completely filling the opening.
13) The jaw sawing action, fluid excretion, and throat vacuum are continued until the throat cavity fills again.
14) The crop is ingested.
15) The processes are repeated until the leech is full.
16) The leech detaches and is removed. (The leech takes less than one hour to fill itself.)
17) The wound continues to bleed for several hours.
18) Another leech can be placed on the extraction site.
It is noted that some authors claim that the sawing action of the jaw occurs only in the initial phase of attachment to produce a wound. None of the authors offer proof of this assertion. Some reason that the action would reduce the seal around the mouth. Others state that the force of the vacuum would restrict any motion. My reasoning is that jaw motion during extraction maintains the wound clearance without increasing the size of the wound. Also, the anticoagulant helps keep the blood flowing but is not the only means of maintaining flow. For these reasons, the AHM (Artificial Hirudo Medicinalis) is designed for simultaneous extraction, secretion and jaw motion.
Air pumps of varying size and quality are common in modern society. Vacuum pumps are mainly used for industrial and scientific applications. In medicine, pumps are used for fluid transfer and as actuators for mechanical instruments. Multi-chambered pumps are available to deliver different pressures simultaneously. One such pump is used to drive a therapeutic sleeve for mechanically massaging anus and legs (Healthtronics Medical Equipment Corp., Dallas, Tex.). These pumps are digitally controlled to provide precise time varying pressures. While such pumps are freely available, none are known to be utilized in conjunction with an artificial leech, as contemplated in the system of the present invention.
Machining technology over the past decade has lead to a new field of fabrication technology know as Micro Electro Mechanical Systems (MEMS). These new fabrication methods are able to produce mechanical parts with dimensions on the order of 50 um and resolutions of less than 1 um. Though the leech is about 5 cm long and the attached head is about 1 cm in diameter, building an artificial leech would require the use of micro technology, since the leech jaws and teeth are very small and require actuation while a vacuum is present. To date, such a design is believed unattained by others.
In 1995, Smoot and others published on article in the Journal of Reconstructive Microsurgery, describing the application of a small vacuum vessel over a puncture wound in a rat. The wound was placed on a site of tissue re-attachment to show the effect of force blood extraction. The wound was washed during extraction with a saline solution. Smoot states the need for an artificial leech since biological xe2x80x9cleeches increase the possibility of infection . . . xe2x80x9d. Also, the brief feeding time of a single leech is not sufficient to completely remove congestion in the effected tissue. For these reasons, the authors promote the use of mechanical means for compulsory blood extraction.
Medical researchers sometimes refer to a xe2x80x9cmechanical leechxe2x80x9d when they describe the use of a vacuum shunt to remove fluid from a site of reconstructive surgery. The device is not at all like a medicinal leech. It has the similarity of extracting blood from a body cavity by reduced pressure, but is not a leech in the sense of this invention.
Lastly, a medical instrument maker in France named Luer sold a so-called xe2x80x9cartificial leechxe2x80x9d in the 1860""s comprising a scarifier and two suction tubes, thus not simulating a leech at all, but instead providing a somewhat primitive suction means for drawing blood from the patient.
Thus, while the prior art has contemplated devices which evidence attempts at providing a replacement for the leech, it is submitted that a suitable replacement is not evidenced in prior teachings.
Unlike the prior art, the present invention provides a blood extraction system which provides the effectiveness of the medicinal leech, but without the limitations thereof
The idea for this system began in July of 1992 when the inventor first saw a CNN news report on the use of leeches in medicine. The report showed a leech on the tip of a surgically reattached toe. The leech was necessary to reestablish blood flow into the previously severed limb.
After studying the anatomy and operation of a leech, it became clear to the inventor that a mechanical device could be built that would preform all of the functions of the leech, and could be monitored and controlled by the user, utilizing micro miniature design and manufacturing techniques. With the availability of electronic control systems to operate a pump drive, the devices proposed as a leech replacement can be used with detailed feedback data for analysis by the attending physician.
The Artificial Hirudo Medicinalis (AHM) forming the ACBES of the present invention consists of two major sections. The first is the AHM attachment device that mechanically functions as a biological leech head. The second is a pump driver that operates the AHM device. The pump is easily manufactured using current pump technology common in the medical field. The AHM device, however, is believed unique at present, requiring fabrication techniques using newly developed micro technology that can produce miniature device structures with micrometer tolerances.
A special hose with three channels connects the AHM device to the pump driver. This hose can be manufactured using current technology developed for the production of micro tubing.
The AHM could not have been built previously due to the lack of fabrication methods. Recent advances in micro fabrication techniques has enabled the production of these devices. Some aspects of the structures can be produced by precision engineering, however the major parts can only be mass produced cost effectively by the new methods. For example, the jaw pieces are flat (0.25 mm thick) and have teeth with 0.1 mm dimensions. The new LIGA process of x-ray lithography and electroplating allows for the mass production of these parts without degradation of the master image.
The advances of micro electronics since the 1960s has resulted in smaller and faster computational processors and controllers. These processors have the ability to preform calculations and control electro mechanical devices. Mechanical devices have been built using the methods for the fabrication of microelectronic, however, the scope of application is very limited. New methods designed explicitly for the production of micro machines have been advanced since the early 1980s.
Recent advances in micro mechanical systems have produced miniature mechanical valves to control gas and liquid flow. Micro pumps have been developed based on the valve designs. These devices are electrically operated. In concert with the valve development is the production of micro sensors. For fluid applications, pressure and flow rate are essential parameters. Sensors for measuring these two physical quantities have also been produced.
The availability of the above mentioned devices opens the possibility for the construction of a microfluidic system. A specific application of a fluidic system is the mechanical leech.
There are no other devices on the market that preform the function of the medicinal leech. The AHM device of the present invention is designed to completely replace the use of leeches in medicine. Also, the use of blood extraction can be expanded to a more common use due to the dependability and portability of the devices. An artificial leech must be designed to have the following characteristics that mimic the medicinal leech:
1) Vacuum induction
2) Adhesion to the skin
3) Opening of a wound
4) Supply of anticoagulant, histamine and anesthetic
5) Continual pulsed blood extraction (pulsed refers to the drinking action)
6) Release from the skin
An example of the utilization of the AHM in the above medical procedure could include, for example:
1) placing the extraction chamber of the AHM on the skin at the site intended for blood extraction;
2) initiating a vacuum or other adhesion means in the vicinity of the extraction chamber, in such a manner as to affix the AHM to the skin;
3) dispensing in the vicinity of the exaction chamber an anesthetic, histamine and anticoagulant;
4) initiating mechanical jaw sections against the skin in the vicinity of the extraction chamber to rock, producing a sawing action;
5) forming an incision in the skin by way of the sawing action;
6) initiating a low pressure suction in the vicinity of the extraction chamber, drawing blood from the wound;
7) relieving the suction, allowing the dispensed medication to be assimilated by the wound;
8) continuing sawing action of the jaw, fluid excretion, and increased and decreased low pressure vacuuming of the area in a pulsed fashion;
9) removing the desired fluid from the patient, stimulating circulation in the area of the wound;
10) removing the device;
11) allowing the wound to continue to bleed for a period of time following removal of the device;
12) re-initiating steps 1-11 until the desired treatment is completed.
It is therefore a an object of the present invention to provide an Artificial Hirudo Medicinalis (AHM) which provides controlled, sanitary extraction of fluids from a patient in such a manner as to limit infection, scarring, or discomfort, while promoting monitored, controlled stimulation of the circulatory system of the patient in the vicinity of the wound.
It is another object of the present invention to provide an AHM which requires little in the way of maintenance, is relatively easy to implement, and which provides a more sanitary, controlled treatment therapy when compared to the prior art.
It is still another object of the present invention to provide an Automated Compulsory Blood Extraction System which mimics in certain ways the bloodletting process of the medicinal leech, but without the care requirements, sanitary problems, control, monitoring obligations, and general patient phobia associated with the medicinal leech.
It is still another object of the present invention to provide specialized Automated Compulsory Blood Extraction Systems which are designed for particular specialized treatments.
It is an object of the present invention to provide an Automated Compulsory Blood Extraction System utilizing a single or plurality of AHM""s to provide computerized, monitored removal of fluids from venous inhibited tissue area of a patient.
Lastly, it is an object of the present invention to provide a micro mechanical device which provides a suitable replacement for the medicinal leech, implementing accepted medical techniques utilizing state of the art micro mechanical engineering and electronics.